PSY270 Chapter 2.docx

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4 Feb 2013

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Chapter 2: Cognitive Neuroscience
Cognitive neuroscience: the study of the physiological basis of cognition
Neurons: building blocks and transmission lines of the nervous system
Neurons: The Building Blocks of the Nervous System
To understand the relation between the brain and the mind it is necessary to look within the brain and
observe the small units that make up its structure and the electrical signals that travel in these units.
The Microstructure of the Brain: Neurons
To observe the structure of the brain, 19th-century anatomists applied special stains to the brain tissue,
which increased the contrast between different types of tissue within the brain.
Nerve net: network; believed to be continuous; provided a complex pathway for conducting signals
uninterrupted through the network (the microscopes of the time could not resolve small details)
In the 1870’s, anatomist Camillo Golgi developed a staining technique that involved immersing a thin
slice of brain tissue in a solution of silver nitrate individual cells became stained at random.
Using this technique, Ramon y Cajal determined that the Golgi-stained cells were individual units.
Neuron doctrine:
1) Individual cells transmit signals in the nervous system
2) These cells are not continuous as proposed by the nerve net theory
Cell body: contains mechanisms to keep the cell alive
Dendrites: branch out from the cell body to receive signals from other neurons
Axon (nerve fiber): transmits signals to other neurons
Cajal’s other conclusions about neurons:
1) Receptors: neurons that pick up information from the environment (i.e. neurons in the skin, eye,
and ear)
2) Synapse: small gap between the end of a neuron’s axon and the dendrites or cell body of another
3) Neurons form connections only to specific neurons; usually many neurons are connected together
to form neural circuits.
The Signals That Travel in Neurons
In the 1920s, Edgar Adrian was able to record electrical signals (action potentials) from single sensory
He also found that each action potential travels all the way down the axon without changing its size.
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Neurotransmitter: a released chemical that makes it possible for the signal to be transmitted across the
The intensity of a stimulus can be represented by the rate of nerve firing (how many action potentials go
down the axon as opposed to the shape/height of the action potentials).
Neurons serving different cognitive functions transmits transmit signals to different areas of the brain.
Localization of Function
Localization of function: basic principle of brain organization; specific functions are served by specific
areas of the brain
Cerebral cortex: later of tissue (3 mm think) that covers the brain
Localization for Perception
Primary receiving areas: 4 respective cortical lobes; first areas to receive signals from each other the
Temporal lobe: auditory receiving area
Occipital lobe: vision receiving area
Parietal lobe: skin senses (i.e. touch, temperature, and pain)
Frontal lobe: receives signals from all of the senses and plans an important role in perceptions that
involve the coordination of information received through two or more senses
The primary receiving areas were initially identified by noting the effects of brain damage.
Prosopagnosia (injury to temporal lobe): inability to recognize faces; can recognize people through their
voices/mannerisms and objects
Fusiform face area (FFA): activated by faces
Parahippocampal place area (PPA): activated by pictures representing indoor and outdoor scenes
Extrastriate body area (EBA): activated by pictures of bodies and body parts
Module: an area specialized for a specific function
Localization for Language
Early evidence for localization of function was provided by Paul Broca’s and Carl Wernicke’s studies of
patients whose difficulty in producing and understanding language could be traced to damage in different
areas of the brain.
Broca’s area: area in the frontal lobe specialized for producing language
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